Here is the full list of all 41 The Black Pool achievements.
Complete 1 level in a run
Complete a multiple levels in a playthrough attempt.
Complete two worlds in a playthrough attempt.
Complete three worlds in a playthrough attempt.
Complete four worlds in a playthrough attempt.
Complete the Obsidian world in a playthrough attempt.
Complete the Gloom world in a playthrough attempt.
Complete the Skylands world in a playthrough attempt.
Complete the Icelands world in a playthrough attempt.
Complete the Maroon Fields world in a playthrough attempt.
Complete the Magnus world in a playthrough attempt.
Complete a playthrough attempt on easier difficulty.
Complete a playthrough attempt on as intended difficulty.
Complete a playthrough attempt on a challenge difficulty.
Complete the Shattered Crater world in a playthrough attempt.
Complete an as singleplayer intended playthrough attempt.
Complete an as multiplayer intended playthrough attempt.
Complete a playthrough attempt with a bronze time crunch challenge difficulty.
Complete a playthrough attempt with a silver time crunch challenge difficulty.
Complete a playthrough attempt with a gold time crunch challenge difficulty.
Complete a playthrough attempt with a full heal reduction challenge difficulty.
Complete a playthrough attempt on challenge 4 difficulty.
Complete a playthrough attempt on challenge 5 difficulty.
Complete a playthrough attempt on challenge 6 difficulty.
Complete an as intended playthrough attempt with no deaths.
Kill an enemy in a multiplayer playthrough attempt.
Revive a friend in a multiplayer playthrough attempt.
Kill a boss in a multiplayer playthrough attempt.
Accumulate 10000 kills.
Accumulate 20000 assists.
Deal over 9000 damage in a single hit.
Complete the Jagged Peaks world in a playthrough attempt.
Complete the Molten Pillars world in a playthrough attempt.
Complete an Enemy Rank playthrough attempt on 100% + Boss difficulty.
Complete a Badder Bosses playthrough on All Bosses difficulty.
Complete a playthrough attempt on challenge level 7 difficulty.
Complete a playthrough attempt on challenge level 8 difficulty.
Complete a playthrough attempt on challenge level 9 difficulty.
Complete a playthrough attempt on challenge level 10 difficulty.
Complete a playthrough attempt on challenge level 11 difficulty.
Complete a playthrough attempt on challenge level 12 difficulty.